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000
FXUS65 KPSR 221121
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
421 AM MST Mon Apr 22 2024

.Update...12Z Aviation Discussion

&&

.SYNOPSIS...
Unseasonably warm temperatures under mostly sunny skies will
continue into midweek with the warmest readings occurring today
as highs top out in the upper nineties across a good portion of
the lower deserts. A cooling trend will begin Tuesday before the
first in a series of weather systems moves through the region
Wednesday and Thursday. By Thursday, temperatures are forecast to
retreat back to around or just below seasonal normal. Winds will
also increase by midweek resulting in gusty afternoon and evening
winds each day through the end of the week.

&&

.DISCUSSION...
Yesterday`s temperatures easily topped out in the mid to upper 90s
across the lower deserts with Phoenix Sky Harbor recording its
first 100 degree day of the year. Current objective analysis
shows generally clear skies across the region under a weak ridge
moving in from the west. This ridge with H5 heights around 580dm
will again allow for another very warm day today with highs
essentially mirroring yesterday.

Starting tonight, a Pacific trough will develop west of
California and begin to dampen our heights aloft. This will
start a slow cooling trend, lowering highs on Tuesday into the
lower 90s across the western deserts to the mid 90s in the Phoenix
area. This dry trough is then expected to enter southern
California later in the day Wednesday before tracking through
Arizona Thursday morning. Winds will increase ahead of the trough
starting Tuesday with daytime wind gusts as high as 25 mph over
the western deserts to then areawide starting Wednesday. Behind
the dry cold front on Thursday, we expect to see daytime highs
falling back into the 80s with NBM guidance mostly calling for
readings in the lower 80s to around 85 degrees, or a few degrees
below normal.

Ensemble guidance then shows the progressive weather pattern will
persist through the rest of the week with broad troughing
continuing across the Western U.S. This will continue to support
breezy to locally windy conditions each day through at least
Saturday and periods of high clouds. Guidance is still supportive
of a stronger shortwave trough tracking either directly through
our region or glancing across the northern portion of our region
late Friday into Saturday. Either track would keep our
temperatures near normal through the weekend with highs most
likely in the mid 80s. This system is also likely to contain a bit
more moisture than the midweek disturbance, but it should mostly
only bring low end rain chances for the Arizona high country.

&&

.AVIATION...Updated at 1120Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns are expected during the TAF period. Winds
will follow diurnal tendencies with a slower than usual afternoon
switch to the W this afternoon, likely leading to a brief period
of S`rly crosswinds at KPHX. Speeds will remain generally light
aob 10 kts, with occasional gusts in the mid-teens through the
day. Besides a FEW passing high clouds, skies will remain mostly
clear through Tuesday morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected during the TAF period. Winds
will follow diurnal tendencies with occasional gusts between 15-20
kts at both terminals this afternoon. Other than a FEW passing
high clouds, skies will remain mostly clear through Tuesday
morning.

&&

.FIRE WEATHER...
Dry conditions with above normal temperatures will persist early
this week with winds steadily becoming more breezy ahead of an
approaching weather system set to move through midweek. Afternoon
humidity levels will continue to fall to around 10% following
poor to fair overnight recovery of 20-40%. Cooler weather arriving
during the latter half of the week will allow an improvement to
RH with afternoon values only falling into a 15-25% range. As this
weather disturbance moves through the region later in the week,
very breezy conditions will also occasionally impact districts
with afternoon gusts commonly reaching 20-30 mph. Given this
combination of winds and humidity levels, a periodic elevated fire
danger should be planned for during the second half of the week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Kuhlman
AVIATION...RW
FIRE WEATHER...18/Kuhlman